In HVAC units, heat exchangers, due to changing temperature and other conditions within an essentially closed environment, end up forming condensate from the air inputted into the HVAC unit. It is undesirable for excess humidity or condensate to remain in the HVAC unit, or to be distributed downstream of the heat exchangers after the air is conditioned in the unit to the outside areas, such as the passenger and other motor vehicle compartments.
In prior art HVAC unit, this undesirable condensate has often been drained from the area of the heat exchanger, such as an evaporator, by exhausting and/or evacuating the condensate from areas beneath the evaporator via a separate or ‘segregated’ channel which is found away from the main airflow path through the HVAC unit, and, particularly, the airflow path coming from the air propulsion device or blower. The air in this airflow path, therefore, flows, after blower, into an expansion zone and possible turning housing downstream of the blower expansion zone. In most cases, the condensate channel or drain is found underneath the blower or blower expansion region in a separate or segregated fashion or downstream of the evaporator. The drain is separate from the main air flow function of the HVAC. Prior art HVAC's, therefore allow the water to drain unhindered by the main airflow in the HVAC and, the drain air path is never exposed to the blown airflow upstream of the evaporator. Because of this HVAC architecture, prior art HVAC units are often designed so that condensate in the drain or channel does not interact with the blown air of the HVAC itself in any appreciable way. Hence the condensate drains away freely, unhindered or disturbed by the airflow from the blower in the HVAC.
The present architectures mean that if a drain were open up to an area at or just downstream of the blower, a negative impact would result due to the fact that there would be a direct open air path allowing drainage wall to be entrained into the airflow path to HVAC unit from the blower expansion zone through the drain to the exterior of the HVAC unit. An open drain anywhere between the area of the blower expansion zone up to the evaporator intake region, (possibly a turning area), would normally be thought of as a detriment to the airflow quantity requirement of the unit if, an excessive quantity of air escaped.